More than 100 Conservative MPs have written to the prime minister urging him to cut subsidies for wind turbines.

They also want planning rules changed to make it easier for local people to object to their construction.

The Tory MPs - joined by some backbenchers from other parties - questioned the amount of money going to the sector during "straitened times".

But the government said wind farms were a "cost-effective and valuable part of the UK's diverse energy mix".

The challenge to the coalition's policy presents an immediate problem for the new Energy and Climate Change Secretary, Ed Davey. He was promoted to the job following the resignation of fellow Liberal Democrat Chris Huhne last Friday.

Lib Dem president Tim Farron told BBC's Andrew Marr Show that Mr Davey was a "very, very capable man" and an "outstanding environmentalist" who would take projects forward.

'Straitened times'

The government wants renewable sources, such as wind, to provide 15% of the UK's energy supply by 2015.

Analysis

By Mike SergeantPolitical Correspondent, BBC News

The wind farm revolt is the first test for the new Energy Secretary Ed Davey.

He's already said he wants to follow Chris Huhne's priorities, and wind power was certainly one of them.

For the 100-plus Conservative MPs who signed the letter, the politics of calling for a subsidy cut are understandable. Many are in rural constituencies where there's plenty of local opposition to new turbines.

But the Liberal Democrats are under pressure to show that ambitious emissions targets aren't going to be junked.

The signatories of this letter say they're not anti-renewable, just concerned about the level of support for onshore wind energy.

This could develop as a tricky issue for the coalition.

It admits that this is "currently more costly" than using fossil fuels, with hundreds of millions of pounds spent on subsidising wind farms each year.

State help is being cut under plans set out by ministers last year, but MPs have demanded an acceleration.

"In these financially straitened times, we think it is unwise to make consumers pay, through taxpayer subsidy, for inefficient and intermittent energy production that typifies onshore wind turbines," they wrote in the letter, seen by the Sunday Telegraph.

The politicians also expressed concerns that the proposed National Planning Policy Framework "diminishes the chances of local people defeating onshore wind farm proposals through the planning system".

Organised by backbencher Chris Heaton-Harris, the letter's 101 Tory signatories include senior figures such as David Davis, Bernard Jenkin and Nicholas Soames.

Another is Tory MP Matthew Hancock, a close ally of Chancellor George Osborne.

Mr Heaton-Harris said two Liberal Democrats, two Labour MPs and one Democratic Unionist were also among his backers.

'Party divided'

BBC chief political correspondent Gary O'Donoghue said the signatories were not against renewable energy per se, but believe onshore wind got far too much money.

For Labour, shadow energy and climate change secretary Caroline Flint said: "Britain should be a world leader in wind energy. We need to put jobs, growth and reducing energy bills first, but David Cameron is failing to do this. We just get a Tory party divided amongst itself...

WIND ENERGY

The first UK onshore wind farm opened in Delabole, Cornwall, in 1991

There are currently 309, with another 252 projects having gained consent

By 2007, wind power accounted for 2.2% of UK electricity supply

Source: RenewableUK

"If Tory MPs want to turn the clock back on renewable energy, it will be the public who pay the price through higher energy bills, as we become more reliant on volatile fossil fuel prices."

But a Downing Street spokeswoman said: "We need a low-carbon infrastructure and onshore wind is a cost effective and valuable part of the UK's diverse energy mix."

She added: "We are committed to giving local communities the power to shape the spaces in which they live and are getting rid of regional targets introduced by the last government.

"The draft framework also aims to strengthen local decision making and reinforce the importance of local plans."

Mr Huhne resigned as Energy and Climate Change Secretary on Friday after hearing he faced a charge of perverting the course of justice over a 2003 speeding case, a claim he denies.